Python Tutorial ( PDFDrive )

If you click hello.py, then this produces the following output:
Content-type:text/html
Hello Word! This is my first CGI program
This hello.py script is a simple Python script, which is writing its output on STDOUT file i.e., screen. There is one
important and extra feature available which is first line to be printed Content-type:text/html\r\n\r\n. This line is
sent back to the browser and specify the content type to be displayed on the browser screen.
Now, you must have understood basic concept of CGI and you can write many complicated CGI programs using
Python. This script can interact with any other exertnal system also to exchange information such as RDBMS.
HTTP Header
The line Content-type:text/html\r\n\r\n is part of HTTP header which is sent to the browser to understand the
content. All the HTTP header will be in the following form:
HTTP Field Name: Field Content
For Example
Content-type: text/html\r\n\r\n
There are few other important HTTP headers, which you will use frequently in your CGI Programming.
Header
Content-type:
Expires: Date
Location: URL
Last-modified: Date
Content-length: N
Description
A MIME string defining the format of the file being returned. Example is Contenttype:text/html
The date the information becomes invalid. This should be used by the browser to
decide when a page needs to be refreshed. A valid date string should be in the
format 01 Jan 1998 12:00:00 GMT.
The URL that should be returned instead of the URL requested. You can use this
field to redirect a request to any HTML file.
The date of last modification of the resource.
The length, in bytes, of the data being returned. The browser uses this value to
report the estimated download time for a file.
Set-Cookie: String
CGI Environment Variables
Set the cookie passed through the string
All the CGI program will have access to the following environment variables. These variables play an important
role while writing any CGI program.
Variable Name
CONTENT_TYPE
CONTENT_LENGTH
HTTP_COOKIE
Description
The data type of the content. Used when the client is sending attached content to
the server. For example, file upload, etc.
The length of the query information. It's available only for POST requests.
Returns the set cookies in the form of key & value pair.
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